This invention relates generally to an apparatus for illuminating license plates using one or more light emitting diodes in conjunction with a reflector.
Government regulations for illuminating license plates exist at both the federal and sometimes the state level. Federal regulations for illuminating license plates are expressed in Federal Motor Vehicle Safety Standards (FMVSS). These standards require the ratio of illumination intensity measured at the two highest and the two lowest circular test points on the license plate not exceed 20:1. Additionally, the minimum illumination per test point must be at least 0.75 Ft-c. There are eight test points proscribed as being approximately one inch in diameter. Four are located on centers that are spaced one inch from each corner. The remaining four are located one inch from the lengthwise centerline and one inch from the top and bottom edges. A figure illustrating the positioning of these test points may be found in U.S. Pat. No. 5,067,057 to Stapel issued Nov. 19, 1991, FIG. 1 of which is herein incorporated by reference. The illumination is substantially uniform if the ratio of illumination intensity is within the above described FMVSS limit.
A variety of solutions to the government requirements exist. Many are elaborate structures mounted near the license plate having one or more lamp assemblies. These assemblies generally depend on incandescent bulbs and/or filaments as a light source. Shortcomings of such light sources are finite lifetimes, sensitivity to vibration and mechanical shock as well as power consumption, heat generated and size and weight. The FMVSS require an even distribution of light that is not too strong and not too weak. Thus, known lamp assemblies often require various combinations of condenser and/or diffuser lenses to be used in conjunction with the light source to refract the light so that it will illuminate the license plate evenly across the whole surface of the plate.
The addition of lenses and/or other optical components may add to the cost and complexity of the lamp assembly. Other problems in meeting government requirements include the need to prevent light from escaping from the lamp assembly in a rearward direction. Some state regulations regarding vehicle light allow only 50 millicandelas or less of white light to be emitted to the rear of the vehicle. Many of the currently produced license lamps are painted on the side to the rear, or require a bracket or other opaque element between the lamp and the rear of the vehicle to prevent white light from traveling in that direction.
The present invention addresses one or more of the above problems in a novel and nonobvious way.
In one form the present invention is an apparatus for illuminating a license plate of a vehicle without a lens. The apparatus includes a housing and a reflector positioned within the housing. The apparatus further includes a light emitting diode positioned within the housing. The light emitting diode projects light directed at the reflector. The reflector has a surface geometry for redirecting the light through a window in the housing such that it substantially uniformly illuminates the license plate.
In another form of the present invention there is an apparatus for illuminating a license plate of a vehicle. The apparatus includes a light emitting diode and a curved free form reflector. The apparatus further includes a housing substantially enclosing the diode and the reflector. The reflector in the housing redirects light projected by the diode through a window in the housing toward the license plate.
In another form of the present invention there is an apparatus for illuminating a license plate of a vehicle. The apparatus includes a plurality of light emitting diodes mounted to a substrate. The apparatus further includes a plurality of reflector segments, each reflector segment corresponding to one of the plurality of light emitting diodes. The apparatus also includes a housing substantially enclosing the plurality of light emitting diodes and the plurality of reflector segments. Each reflector segment redirects light projected by the corresponding one of the plurality of light emitting diodes through a window in the housing toward the license plate.
In yet another form of the present invention there is an apparatus for illuminating a license plate of a vehicle. The apparatus includes a light emitting diode projecting light directed substantially away from the vehicle and a housing substantially enclosing the light emitting diode. The apparatus further includes lensless means within the housing for substantially preventing light from the diode from escaping the housing in a rearward direction and for redirecting the light through a window in the housing toward the license plate.
One object of the present invention is to provide a unique light emitting diode license plate lamp design.
Related objects and advantages of the present invention will be apparent from the following description.